Process for making mesh-sieves



July 14, 1931. R. HERRMANN 1,814,598

' PROCESS FOR MAKING MESH SIEVES Filed Feb. 16, 1928 MW 4 m4 Patented July 14, 1931 UNITED STATES PATENT OFFICE BUDOIIF EERWNN, OF DRESITEN, GERMANY Application filed February 16, 1928. Serial No. 254,828.

In the manufacture of mesh-sieves it is not only necessary to attend to the uniformity of the widths of the meshes but also to the rigid fastening of the crossing bars or wires for the purpose of preventing an alteration of the posltlon of the wires caused by the movement of the sieves and by the material running on the sieves and in consequence an alteration of the width of the meshes. Consequently the wires of mesh webs are connected in such a manner that a substantially uniform bending of the warp and weft wires takes place. Be-

sides this, wire-webs are sometimes,-after' their manufacture, rolled together under pressure so rigidly that a mutual engagement of the wires at the crossing points and thereby a rigid fastening is insured.

However, in the manufacture ofwire-webs the thickness of the wires and the shape of the section as well as the width of the meshes are bound to certain limits. A weaving of wire is only possible up to a certain thickness and even the width of the meshes may not exceed a certain size, as else the holdfast of the wires is disturbed.

Therefore it was proposed to manufacture thick sieves arranged with large meshes, as used for instance for classifying coarser materials, in such a manner that the single wires are provided with bends arranged at distances corresponding to the desired widths of Q meshes and the wires thus obtained are then connected to form a mesh-sieve. In this manner wires of any large thickness as well as mesh-sieves of any desired width ofthe mesh apertures can be manufactured.

It is true that in mesh-sieves of this kind a solid transversal position is, at the cross ing points of the wires, given to said wires,

by the bends into which the transversal wires are inserted, in other words in the direction of the longitudinal axis of said transversal wires but not in the longitudinal direction of the latter. In consequence small changes or alterations in the position of the wire will take place while strengthening the sieves,

said changes gcausing irregularities of the mesh-widths and an incorrect classification.

Consequently it is necessary to give to the wires inserted into the bends arigid position also their longitudinal direction. This ismost suitably done by arranging grooves in the wires, said wires being of a width and shape equal to those of the bent transversal wire situated below. The wire first men- 55 tioned will rest in engagement with the transversal wire, so that the safe and mutual position of the wires is insured by the bends and the grooves.

Now it has been found that irregularities no in the distribution of the bends and the grooves are frequently caused during the forming of said grooves, i. e., that the distance between a bend and an adjacent groove is not always kept equal,'so that bars unic5 formly free of objections could not'be manufactured. In accordance with the lengths of the sieve-bottoms being constructed, wires up to six meters in length are encountered which must be provided with' bends and grooves at absolutely even distances. The irregularities resulting during the pressing and punching of the grooves produce alterations in the distribution or division of the bends and the grooves to such an extent that not only are irregular widths of meshes produced but even that a connection of the wires is no more possible.

In case the bends are pressed in at the lower side of the wires, an extension of the so wires will take place which is more. or less noticeable according to the hardness of the material. If the grooves are laterally punch-ed, an extension of this part of the wire is caused by a displacement of the material taking place at the lower side of the wires, in such a manner that a straightening will again be necessary later on By extending the lower portion of the wire as well as by the later straightening procedure irregularities equal to those caused 1n the first-mentioned case will occur.

Now, for the purpose of obtaininga uniformity of the division, 1. e., in the distance between a bend and a groove in the wires, each single bend and an adjacent groove are simultaneously produced according to the present invention in one operation within a pressing-mold in such a manner that the distance between the middle line of the bend and the middle line of the groove is absolutely and precisely maintained.

In case wires of that kind provided with bends and grooves are connected to form a mesh-sieve, the precise width of the meshes is given and insured by the simultaneous manufacture of each single bend and groove. Therefore, according to the new process a precision mesh-sieve with a perfectly uniform and unvariable mesh-Width is obtained. Inview of the fact that the division itself is precisely maintained, it is possible to keep the bends to be pressed into the profile wires precisely equal to the profile of the bent transversal wires, so that any play of the engaging wires at the crossing points is excluded. 1

Therefore the advantage is obtained which consists in that not only a precise width of mesh but also a perfectly rigid seat or rigid connection of the crossing wires at the crossing places is insured.

Fig. 1 shows in a vertical section the pressmold necessary for "the manufacture of the wires according to the new process. Fig. 2 shows in plan a mesh-sieve manufactured according to the present process; Fig. 3, a section according to the line 3-3 in Fig. 2; and Fig. 4, a plan according to line 4-4 in Fig. 2. Fig. 5 shows the manner of inserting two crossing wires one into another, while Fig. 6 shows various cross-sectional shapes of 'the wires used for the manufac ture of mesh-sieves.

As seen in Fig. 1 a is the bottom-die provided with a groove 7) for the bends in the wires and with a projection 0 for the formation of the grooves situated at the lower side of the wires. 01 is the punch, arranged with a projection e which forms a bend in the wire f situated between the bottom-die and the punch during the pressing-procedure. In view of the fact that the bend g and the groove h of 'the wire are produced within a press-mold in one procedure, the distance '5 between the middle-line of the bend and the middle-line of the groove is constantly the same, so that the advantages mentioned above are obtained.

The wires arranged with bends and grooves and manufactured in the manner described are connected so as to form a mesh-sieve as seen from Figs. 2 to 5. Owing to the maintenance of the precise distance between the middle-line of the bend and that of the groove, a precise width of the meshes as against bending and a larger open area for the passage of the material.

Without in any way departing from the scope of the invention it will be readily understood that several wires ma simultaneously be placed side by side wit in a pressmold and provided with bends and adjacent grooves.

What I claim is:

The process for the manufacture of meshsieves from bars or wires, which process includes forming a bend in one portion of each Wire, forming a' groove in an adjacent portion of the same wire, and retaining the wire positively against bending at all points except that where the said bend is formed, said bend and groove being formed at points a predetermined fixed distance apart, in a single procedure without readj usting the position of the wire, and by forming motion in a direction substantially perpendicular to the straight longitudinal direction of the wire; the wires thus bent and grooved being then interwoven and placed so that the bent portions of the wires running in one direction rest in the grooves formed in the wires running transversely thereto at each crossing point.

In testimony, that I claim the foregoing as my invention, I have signed my name this 1st day of February, 1928.

. RUDOLF HERRMANN. 

